AES E-Library

AES E-Library

A Subband Domain Downmixing Scheme for Parametric Stereo Encoder

Parametric Stereo (PS) coding describes stereo audio signal with a monaural signal and a set of spatial parameters. This paper describes a signal-dependant, subband-domain downmixing scheme for PS encoder to obtain the monaural signal. The downmixing is performed on the subband signal output from PS analysis filtering, hence no extra signal decomposition is required. The scheme is able to minimize phase cancellation by performing phase alignment of the stereo signals prior to the mixing. In addition, power equalization ensures preservation of the overall power of the original stereo signal in the monaural downmixed signal. Additional computational requirement can be kept low by making use of the available PS spatial parameter data for the phase alignment. Testing on synthetic and real-life audio recording shows a good performance especially for audio recording with significant out-of-phase side signal component.